The West should consider using all its tools to help Ukraine, including sending defensive weapons, NATO's top military commander said on Sunday.

"I do not think that any tool of U.S. or any other nation's power should necessarily be off the table," U.S. Air Force General Philip Breedlove told a Brussels conference when asked if he was in favour of sending defensive weapons to Ukraine.

Without naming Russia, Breedlove said that diplomatic, information, military and economic tactics were being used against Ukraine.

"And so we, I think, in the West should consider all of our tools in reply. Could it be destabilising? The answer is yes. Also, inaction could be destabilising," said Breedlove, who is NATO's Supreme Allied Commander, Europe, and commander of U.S. European Command.

Breedlove also said that NATO intelligence pointed to "disturbing" military developments on the ground in eastern Ukraine and voiced concern about whether a Ukraine ceasefire deal reached in Minsk last month was being complied with.

"We continue to see disturbing elements of air defence, command and control, resupply, equipment coming across a completely porous border. So there are concerns about whether Minsk is being followed or not," he said, speaking at the Brussels Forum, organised by the German Marshall Fund thinktank.